Feeding Oils to Endurance Horses for Aerobic Performance (part 2)

updated at: Tue 08 Aug 2017

In previous articles, we discussed why endurance horses are designed to operate at peak performance under aerobic conditions, i.e. in the presence of oxygen, and why grain is the enemy of the endurance athlete. We introduced the term ATP which is the chemical form that energy is delivered to the muscles. ATP is derived mainly from carbohydrate and/or fat. It is how the ATP is delivered that determines how well your horse completes, and recovers from, the ride.

During competition, most endurance horses cannot eat nor digest sufficient feed at each veterinary check to produce the ATP required to meet the energy requirements for the next leg/loop. It is essential therefore that you fill up the fuel tank (energy reserves) before the event. A 400kg horse can store approximately only 13,000 cal/kg as glycogen, but a massive 590,000 cal/kg as fat! That is the good news. The bad news is that horses can only use these fat reserves if they are metabolically adapted, fed the right oils, and not overloaded with high Non Structural Carbohydrate (NSC or grain) feeds.

***Horses can store 40 times more energy as fat. Horses can only use body fat if they are fat adapted***

Feeding Oils. There is good logic as to why you should feed oils to an endurance horse. Oils contain 2.5 times more energy than carbohydrate. It produces 3 times more ATP than carbohydrate under aerobic conditions, and horses can store 40 times more energy as fat. It is imperative, however, that the diet remains balanced for carbohydrate, protein, fibre, minerals and vitamins, since overfeeding oils can cause reduced fibre digestion and unbalanced mineral supply. The constraint to efficient fat utilisation however is that the energy (ATP) from fat can only be released when carbohydrate (grain) intake is low, ie. When INSULIN levels are low. Also, it takes 2-3 weeks for a horse to become fat adapted, i.e. for the metabolic pathways, hormones and enzymes to switch to using oil rather than carbohydrates and glycogen.

***Grain produces insulin which switches off the hormones for the utilisation of fat as an energy reserve***

Omega oils? There is a lot of unnecessary confusion about oils. Horses have a small stomach and are designed to eat at least 18 hours a day. Horses don’t have a gall bladder and therefore secrete bile continuously to emulsify the fats. Horses can be fed up to 25% of Digestible Energy as oil. Oils are either saturated or unsaturated, have different carbon chain lengths, and are either non –essential, or essential (cannot be manufactured by the horse). All animals, including humans require a balanced intake of essential oils. It is suggested that the correct balance the essential oils Omega 6: Omega 3 is about 4:1. The problem arises however when we give feeds with high levels of Omega 6 (from grains and polyunsaturated (PUFA) oils rich in linoleic acid (Omega 6) from sunflower, corn, soybean, canola). These feeds can produce Omega 6:3 ratios of 30-40:1 which can cause inflammation and assorted health issues. The approach has been to treat the symptom and not the cause by feeding oils with a high level of Omega 3 from flax, chia, to try and balance the 6:3 ratio.

This approach does not address the underlying issue created by feeding grain based diets, especially for the endurance horse. It is now well accepted that feeding high NSC (grain) diets can cause poor temperament, tendon and ligament problems (lameness) and metabolic issues (insulin resistance, tying up, cushings, laminitis, EMS, and colic). Logically, if you feed less grain, and less Omega 6 oils, you will also reduce the intake of Omega 6, and bring the Omega 6:3 ratio back into balance. More importantly, you may also reduce the metabolic issues caused by NSC (grain) feeding.

This removes the need to feed expensive Omega 3 oils. If horses are grazing pasture, and well prepared hays, they will usually eat enough Omega 3 to meet dietary requirements. (Refer to the great book Equine Applied and Clinical Nutrition, expensive but worth it for all horse owners). Which oil? The key is to select a balance of oils that are palatable, haven’t been highly processed, do not go rancid, provide the correct balance Omega 6:3:9 and that deliver ATP to meet the horses energy demands under aerobic conditions. Most oils are absorbed and transported slowly to the liver via the lymphatics. The medium chain triglyceride (MCT) oils such as coconut oil however are unique in that they are absorbed directly into the portal blood and transported directly to the liver. Coconut oil therefore is used as a non-glucose source of ready energy. One of the main advantages of coconut oil is that when compared to PUFA oils, it improves muscle glycogen storage and utilisation. Most importantly, feeding oils also reduces thermal load, which is critical for recovery under heavy work load and hot conditions.

Why feeding twice a day can be bad. We usually feed our horses twice daily because it suits our busy lifestyle. If we feed high NSC feeds, this creates spikes in both insulin and glucose, which cause hormonal shifts that switch off fat adaptation and fat utilisation pathways. In a published nutritional study of horses at pasture, when given feeds of different NSC content, the sweetfeed (33% NSC) and pelleted (25% NSC) feeds gave large spikes in both insulin and glucose. By comparison, 2.3kg/day of copra meal (10% oil, 11% NSC, 15 MJ digestible energy) did not metabolically increase glucose or insulin (Richards et al 2016 Animal Feed Science and Technology). Copra meal is the only high energy, low NSC feed that can be fed to endurance horses as single feed that does not have a negative influence on insulin and glucose levels.

Our goal is to provide horses with a feed that is high in fibre, provides good sources of oil, and low levels of NSC (low grain). It is impracticable for most people to feed more than twice a day, and therefore it is important to read the feed label and select a feed with low NSC, high digestible energy, and low levels of Omega 6. The next article will discuss how to adapt your horse to a high fat diet, and what other supplements are required to optimise aerobic performance and fat utilisation.